Solar cell module efficacy monitoring system and monitoring method therefor

ABSTRACT

A solar cell module efficacy monitoring system includes a reference module which includes a solar power generation module and is to be maintained in a clean condition, an evaluation module which includes a solar power generation module and is to be covered by dust in an environment, maximum power point tracking devices which track powers of the reference module and the evaluation module and maintain power outputs at maximum points by connected to the reference module and the evaluation module, respectively, and, a PV communication recording device which records power generation results of the reference module and the evaluation module by connected to the reference module and the evaluation module, and a calculation display device which calculates power loss due to accumulation of dust on the evaluation module by connected to the PV communication recording device.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of and claims priority under 35 USC120 to U.S. patent application Ser. No. 14/828,459 filed on Aug. 17,2015 and entitled “Solar Cell Module Efficacy Monitoring System andMonitoring Method Therefor”, which in turn is a continuation of andclaims priority under 35 USC 120 to U.S. patent application Ser. No.14/484,705 filed on Sep. 12, 2014 and entitled “Solar Cell ModuleEfficacy Monitoring System and Monitoring Method Therefor”, which inturn is a continuation-in-part of and based on the InternationalApplication No. PCT/JP2013/001689, filed Mar. 14, 2013, which is basedupon and claims the benefit of priority to under 35 USC 119 to JapanesePatent Application No. 2012-056758, filed Mar. 14, 2012. The entirecontents of these applications are incorporated herein by reference.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a solar cell module efficacy monitoringsystem and a monitoring method therefor.

Description of Background Art

In recent years, as earth's resources decrease and eco-consciousnessgrows, countries are putting efforts on development of alternativeenergies such as solar energy, wind energy, geothermal energy andhydro-energy, of which power generation using solar light attracts themost attention. Amount of solar energy reaching earth's surface each dayis equivalent to about one quarter of world's oil reserves, and solarenergy is an inexhaustible natural resource. Solar power generation isclean and has advantages such as that it does not cause environmentalpollution, does not involve resource depletion and can be easilyincorporated in a building. Further, along with rapid advancement insemiconductor materials in recent years, solar light photoelectricconversion efficiency continues to improve and thus, this also resultedin wide application of solar cell modules (for example, Japanese PatentLaid-Open Publication No. 2012-015412). The entire contents of thispublication are incorporated herein by reference.

SUMMARY OF THE INVENTION

According to one aspect of the present invention, a solar cell moduleefficacy monitoring system includes a reference module which includes asolar power generation module and is to be maintained in a cleancondition, an evaluation module which includes a solar power generationmodule and is to be covered by dust in an environment, maximum powerpoint tracking devices which track powers of the reference module andthe evaluation module and maintain power outputs at maximum points byconnected to the reference module and the evaluation module,respectively, and, a PV communication recording device which recordspower generation results of the reference module and the evaluationmodule by connected to the reference module and the evaluation module,and a calculation display device which calculates power loss due toaccumulation of dust on the evaluation module by connected to the PVcommunication recording device.

According to another aspect of the present invention, a method formonitoring solar cell module efficacy includes obtaining a rated outputfrom a reference module of a solar cell module, obtaining an actualgenerated power from an evaluation module of the solar cell module,obtaining power loss ΔPd due to accumulation of dust on the evaluationmodule, obtaining power loss ΔPt due to operation temperature of thesolar cell module, obtaining power loss ΔPm due to maximum power pointtracking of the solar cell module, and calculating power loss ΔP of thesolar cell module during actual operation from a formula, ΔP=the ratedoutput of the solar cell module−(actual generated power of the solarcell module+ΔPd+ΔPt+ΔPm). The reference module is to be maintained in aclean condition, and the evaluation module is to be covered by dust inan environment.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the invention and many of the attendantadvantages thereof will be readily obtained as the same becomes betterunderstood by reference to the following detailed description whenconsidered in connection with the accompanying drawings, wherein:

FIG. 1 illustrates a block diagram illustrating a schematicconfiguration of a main part of a solar cell module efficacy monitoringsystem 1 according to an embodiment of the present invention;

FIG. 2 illustrates a block diagram illustrating a schematicconfiguration of a main part of a solar cell module efficacy monitoringsystem 2 according to another embodiment of the present invention;

FIG. 3 illustrates a block diagram illustrating a schematicconfiguration of a main part of a solar cell module efficacy monitoringsystem 3 according to yet another embodiment of the present invention;and

FIG. 4 illustrates a block diagram illustrating a schematicconfiguration of a main part of a solar cell module efficacy monitoringsystem 4 according to yet still another embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The embodiments will now be described with reference to the accompanyingdrawings, wherein like reference numerals designate corresponding oridentical elements throughout the various drawings.

FIG. 1 illustrates a block diagram of a schematic configuration of amain part of a solar cell module efficacy monitoring system 1 of anembodiment according to the present invention. FIG. 2-4 illustrate blockdiagrams illustrating schematic configurations of main parts of solarcell module efficacy monitoring systems (2-4) according to otherembodiments of the present invention.

A solar cell module efficacy monitoring system 1 according to anembodiment of the present invention is for calculating power generationloss of a solar cell module including power loss due to dustaccumulation, power loss due to operating temperature of the solar cellmodule and power loss due to maximum power point tracking, and forcalculating, by making a comparison with a rated output, power loss ofthe solar cell module during actual operation to timely reflect powergeneration efficiency and to further issue an alarm and an advice.

With reference to FIG. 1, a solar cell module efficacy monitoring system1 according to an embodiment of the present invention is described. Thesolar cell module efficacy monitoring system 1 according to the presentembodiment includes: a reference module 11 that is a solar powergeneration module and a surface of which is constantly maintained in aclean condition; an evaluation module 12 that is a solar powergeneration module and a surface of which is covered by dust due tofactors such as environment and climate; maximum power point trackingdevices (13, 14) that, by being respectively connected to the referencemodule 11 and the evaluation module 12, track maximum power points ofthe two modules and maintain the two modules in such a manner that thetwo modules output maximum powers; a PV communication recording device15 that, by being connected the reference module 11 and the evaluationmodule 12, reads power values of the two modules using a predeterminedclamp meter and records the power values; temperature sensors (21, 22)that, by being respectively connected to the reference module 11 and theevaluation module 12, detect operating temperatures of the two modules;a sensor communication recording device 28 that is connected to a raingauge 23, a fine particle detector 24, a thermo-hygrometer 25, ananemovane 26 and a solarimeter 27 and is for recording data detected bythese sensors, the rain gauge 23 detecting a rainfall value in theenvironment, the fine particle detector 24 detecting a number of fineparticles in the environment, the thermo-hygrometer 25 detectingtemperature and humidity in the environment, the anemovane 26 detectinga wind speed and a wind direction in the environment, and thesolarimeter 27 detecting a solar radiation value in the environment; acalculation display device 16 that is connected to each of the sensorcommunication recording device 28 and the PV communication recordingdevice 15 and, based on data received from the sensor communicationrecording device 28 and the PV communication recording device 15,calculates power loss of the evaluation module 12 due to dustaccumulation; a calculation display device 29 that is connected to eachof the sensor communication recording device 28 and the PV communicationrecording device 15 and, based on data received from the sensorcommunication recording device 28 and the PV communication recordingdevice 15, calculates power loss due to the operating temperature of theevaluation module 12 and power loss due to the maximum power pointtracking; a calculation display device 31 that is connected to each ofthe calculation display device 16 and the calculation display device 29and, based on relevant data such as the power loss due to dustaccumulation that is calculated by the calculation display device 16,the power loss due to the operating temperature of the solar cell moduleand the power loss due to the maximum power point tracking that arecalculated by the calculation display device 29, and actual generatedpower of the evaluation module 12 and a rated output of the referencemodule 11, calculates power loss of the solar cell module during actualoperation; alarm devices (17, 30, 32) that, by being respectivelyconnected to the calculation display devices (16, 29, 31), issue analarm and an advice when the respective losses that are calculated bythe calculation display devices (16, 29, 31) exceed a specific value;and a power supply device 71 that supplies power to the respective partsof the solar cell module efficacy monitoring system 1.

A description is given of how the respective parts of the solar cellmodule efficacy monitoring system 1 are used to calculate the power lossdue to dust accumulation, the power loss due to the operatingtemperature of the solar cell module, the power loss due to the maximumpower point tracking, and the power loss of the solar cell module duringactual operation.

For the power loss due to dust accumulation, in the solar cell moduleefficacy monitoring system 1, the reference module 11 and the evaluationmodule 12 are used to compare an effect of dust in the environment onthe power generation efficiency of the solar cell module.

By being respectively connected to the maximum power point trackingdevices (13, 14), the reference module 11 and the evaluation module 12are maintained in such a manner that the two modules output maximumpowers. The reference module 11 and the evaluation module 12 are alsorespectively connected to the PV communication recording device 15.Power generation data of the reference module 11 and the evaluationmodule 12 is recorded in the PV communication recording device 15 andthereafter is transmitted to the calculation display device 16 forcalculating the power loss due to dust accumulation. The calculationdisplay device 16 calculates differences in power generation (includinga power generation amount, power generation efficiency, an integratedpower generation amount, and the like) between the evaluation module 12,which is covered by dust, and the reference module 11.

A part of the results (detection results of, for example, temperaturesof the modules, rainfall, fine particles, and the like) that aredetected by the respective sensors and are recorded by the sensorcommunication recording device 28 is also transmitted to the calculationdisplay device 16 and is used in the calculation of the power loss dueto dust accumulation. A description will be given later of how thedetection results of the temperatures of the modules, rainfall, fineparticles and the like are used in the calculation of the power loss dueto dust accumulation.

Calculation results of the differences in power generation are furthertransmitted to the alarm device 17. Based on the calculation results ofthe differences in power generation that are calculated by thecalculation display device 16, the alarm device 17 performs monitoringusing, for example, an SPC (Statistical Process Control) statisticalcontrol method and timely issues an alarm and an advice.

The solar cell module efficacy monitoring system 1 also has a functionof calculating and monitoring power loss due to the actual operatingtemperature of the solar cell module and power loss due to the maximumpower point tracking and timely issuing an alarm and an advice.

The detection results of the respective sensors that are recorded by thesensor communication recording device 28 are transmitted to thecalculation display device 29. Power generation results of the solarcell module that are recorded by the PV communication recording device15 are also transmitted to the calculation display device 29.

The calculation display device 29 is capable of calculating andmonitoring the power loss due to the actual operating temperature of thesolar cell module and the power loss due to the maximum power pointtracking. More specifically, by applying calculation methods such ascomputation, correction, regression, calibration and the like withrespect to the received data, the power loss due to the actual operatingtemperature of the solar cell module in the system and the power lossdue to the maximum power point tracking are calculated.

The power loss due to the operating temperature and the power loss dueto the maximum power point tracking that are calculated as describedabove are further transmitted to the alarm device 30. The alarm device30 performs monitoring using the SPC statistical control method andtimely issues an alarm and an advice.

The power loss due to dust accumulation that is calculated by thecalculation display device 16, and the power loss due to the operatingtemperature of the solar cell module and the power loss due to themaximum power point tracking that are calculated by the calculationdisplay device 29, are respectively transmitted to the calculationdisplay device 31. Based on relevant data such as the respective losses,the actual generated power of the evaluation module 12 and the ratedoutput of the reference module 11, the calculation display device 31calculates the power loss of the solar cell module during actualoperation.

The calculated power loss of the solar cell module during actualoperation is further transmitted to the alarm device 32. The alarmdevice 32 performs monitoring using the SPC statistical process controlmethod and timely issues an alarm and an advice.

In the present embodiment, cleaning devices (not illustrated in thedrawings) that maintain surfaces of the reference module 11 and thesolarimeter 27 in a clean condition may be respectively connected to thereference module 11 and the solarimeter 27. Further, washing liquid thatis used by the cleaning devices can be recycled and re-used. Therefore,an embodiment of the present invention also has an advantage as beingwater-saving and eco-friendly.

In a solar cell module efficacy monitoring system 1 according to anembodiment of the present invention, transmission of all data betweenthe respective components (including the data transmission from therespective sensors (21-27) to the communication recording devices (15,28), the data transmission from the communication recording devices (15,28) to the calculation display devices (16, 29), the data transmissionfrom the calculation display devices (16, 29, 31) to the alarm devices(17, 30, 32), the data transmission from the calculation display devices(16, 29) to the calculation display device 31, and the like) can beperformed via wired, wireless or power line connections.

Power supply to the respective parts of the solar cell module efficacymonitoring system 1 may adopt an internal power supply method or anexternal power supply method. The internal power supply method is thatin which power generated by the reference module 11 and the evaluationmodule 12 is feedback-supplied to the power supply device 71 and isfurther supplied from the power supply device 71 to the respective partsof the solar cell module efficacy monitoring system 1. The power supplydevice 71 may also use the external power supply method in which poweris externally supplied to the power supply device 71 and is furthersupplied from the power supply device 71 to the respective parts of thesolar cell module efficacy monitoring system 1.

An embodiment of the present invention has been described using FIG. 1.However, the present invention is not limited to the above embodiment.

For example, as illustrated in FIG. 2, it is also possible to have onlyone calculation display device 33. The power generation data of thereference module 11 and the evaluation module 12 and the detection dataof the respective sensors that is recorded by the communicationrecording device 15 are transmitted from the PV communication recordingdevice 15 to the calculation display device 33. The calculation displaydevice 33 calculates each of the power loss due to dust accumulation,the power loss due to the operating temperature of the solar cell moduleand the power loss due to the maximum power point tracking and, based onthe relevant data such as the respective losses, the actual generatedpower of the evaluation module 12 and the rated output of the referencemodule 11, calculates the power loss of the solar cell module duringactual operation.

An alarm device 34 may be connected to the calculation display device33. The alarm device 34 performs monitoring using the SPC statisticalcontrol method and timely issues an alarm and an advice.

Or, as illustrated in FIG. 3, it is also possible to have threecalculation display devices (35, 36, 37). The power generation data ofthe reference module 11 and the evaluation module 12 and the detectiondata of the respective sensors that is recorded by the communicationrecording device 15 are transmitted from the PV communication recordingdevice 15 to each of the calculation display devices (35, 36, 37). Thecalculation display devices (35, 36, 37) respectively calculate thepower loss due to dust accumulation, the power loss due to the operatingtemperature of the solar cell module, and the power loss due to themaximum power point tracking. The calculated respective losses arefurther transmitted to a calculation display device 38. Based on thepower loss due to dust accumulation, the power loss due to the operatingtemperature of the solar cell module and the power loss due to themaximum power point tracking and based on the relevant data such as theactual generated power of the evaluation module 12 and the rated outputof the reference module 11, the calculation display device 38 calculatesthe power loss of the solar cell module during actual operation.

An alarm device 39 may be connected to the calculation display device38. The alarm device 39 performs monitoring using the SPC statisticalprocess control method and timely issues an alarm and an advice.

The calculation display devices (35, 36, 37) in the above-describedembodiment of FIG. 3 for calculating the power loss due to dustaccumulation, the power loss due to the operating temperature of thesolar cell module and the power loss due to the maximum power pointtracking may be respectively connected to different alarm devices (40,41, 42) as illustrated in FIG. 4. Based on the power loss due to dustaccumulation, the power loss due to the operating temperature of thesolar cell module and the power loss due to the maximum power pointtracking, the alarm devices (40, 41, 42) timely issue an alarm and anadvice.

The above-described embodiments of FIG. 1-4 are merely for describingembodiments of the present invention. The number of the calculationdisplay devices and the number of the alarm devices according to thepresent invention can be arbitrarily combined. The present invention isnot limited to the above-described embodiments. A person of averageskill in the art of the present invention can conceive variousvariations within the scope of present invention.

A method for monitoring solar cell module efficacy according to anembodiment of the present invention is described.

With reference to the above-described configuration of the apparatusaccording to an embodiment of the present invention, calculation methodsfor the power loss due to dust accumulation, the power loss due to theoperating temperature of the solar cell module and the power loss due tothe maximum power point tracking are respectively described.

The power loss due to dust accumulation is indicated using ΔPd; thepower loss due to the operating temperature of the solar cell module isindicated using ΔPt; and the

power loss due to the maximum power point tracking is indicated usingΔPm. The power loss (Δp) of the solar cell module during actualoperation is obtained using the following Formula 1:

the power Loss (Δp) of the solar cell module during actual operation=therated output of the solar cell module−(the actual generated power of thesolar cell module+ΔPd+ΔPt+ΔPm)   Formula 1

In Formula 1, the rated output of the solar cell module is the generatedpower of the solar cell module that is detected based on ASTM E1036standard when the solar cell module is in a standard test condition(temperature: 25° C.; solar radiation intensity: 1,000 W/m2). In thepresent invention, a rated output provided by a manufacturer of thesolar power generation module is used as the rated output of the solarcell module. The actual generated power of the solar cell module is thepower generated in a state in which the evaluation module 12 is actuallyused, that is, in a state in which the surface of the evaluation module12 is covered by dust.

The power loss ΔPd due to dust accumulation is obtained using acalculation method in which the generated power of the evaluation module12 is subtracted from the generated power of the reference module 11.

In order to judge whether or not the surface is really covered by dust(dust accumulation condition) or whether or not the power generationloss is due to system malfunction and other factors, the rain gauge 23and the fine particle detector 24 are also used. When the amount of thefine particles detected by the fine particle detector 24 is high, thepower loss due to dust accumulation should also increase. On the otherhand, when the rainfall value detected by the rain gauge 23 is high,since the surface of the solar cell module is washed and becomes clean,the power loss due to dust accumulation should decrease. When a trenddifferent from that described above is observed, it can be inferred thata factor other than dust accumulation has affected the power generationamount and thus it can be judged that it is necessary to performinspection and verification of the system.

When the surface is covered by dust, the temperature of the solar cellmodule decreases. Therefore, a difference between temperatures of thereference module 11 and the evaluation module 12 that are respectivelydetected by the temperature sensors (21, 22) can be used to help judgingdust accumulation condition.

Calculation of the power loss ΔPt due to the operating temperature ofthe solar cell module is described. When the solar cell module receivessolar light, the temperature gradually rises. When the temperature ofthe solar cell module rises, the power generation amount decreases.Therefore, the power loss ΔPt due to the operating temperature of thesolar cell module can be calculated from the following Formula 2 bycomparing the operating temperature of the evaluation module 12 in anactual operating state and power generation loss in a state of thestandard temperature of 25 ° C.:

ΔPt=P×[{α(T-25)}/{1+α(T-25)}]   Formula 2

In Formula 2, P is the generated power of the evaluation module 12 thatis recorded by the PV communication recording device 15; a is atemperature coefficient of the solar cell module; and T is the operatingtemperature of the evaluation module 12 that is detected by thetemperature sensor 22.

The operating temperature of the solar cell module is detected by thetemperature sensor 22. The temperature sensor 22 may be arranged at anyplace on a front surface or a back surface of the evaluation module 12.Further, the present invention is not limited to the case of having onetemperature sensor 22, but multiple temperature sensors 22 may beprovided. When multiple temperature sensors 22 are provided, an averagevalue of operating temperatures that are detected by the multipletemperature sensors is used as the operating temperature of the module.

However, since the temperature sensor 22 is arranged on the frontsurface or the back surface of the solar cell module, when thetemperature sensor 22 is exposed to wind, there is a possibility that adifference occurs between the temperature detected by the temperaturesensor 22 and the actual operating temperature of the solar cell module.Further, there is a possibility that temperature and humidity in theenvironment cause a difference to occur between the temperature detectedby the temperature sensor 22 and the actual operating temperature of thesolar cell module. Therefore, the thermo-hygrometer 25 and the anemovane26 can be used to correct the operating temperature of the solar cellmodule.

A solar energy amount that can be converted by the solar cell module isdetermined by solar radiation intensity and the temperature of the solarcell module. Since power output of the solar cell module is alsodifferent under different operation environment and condition, a maximumpower point tracking device has been developed. When the solar radiationintensity varies, the maximum power point tracking device can track themaximum power point of the solar cell module and, even when a part ofthe solar cell module is blocked, can maximize the power output of thesolar cell module.

According to an embodiment of the present invention, the two maximumpower point tracking devices (13, 14) are used to track the maximumpower points of the reference module 11 and the evaluation module 12 andto maintain the reference module 11 and the evaluation module 12 in sucha manner that the two modules can output maximum powers at any time.However, when solar light is momentarily blocked, the power of the solarcell module decreases. However, since, in some cases, the maximum powerpoint tracking device cannot track the maximum power point, the powerloss due to the maximum power point tracking occurs. Therefore, anotherfeature of an embodiment of the present invention is that the power lossdue to the maximum power point tracking can be calculated.

In an embodiment of the present invention, the power loss ΔPm due to themaximum power point tracking is calculated by comparing the powergeneration data of the solar cell module and the solar radiation value.More specifically, electric currents and power values of the evaluationmodule 12 that are recorded by the PV communication recording device 15and the solar radiation values that are detected by the solarimeter 22are used to obtain a linear regression relationship between the electriccurrents and the solar radiation values by performing a regressionanalysis, which is a statistical technique. Outliers (for example, ±5%)above or below the regression line are removed and, further, a linearregression relationship between the powers and the solar radiationvalues is obtained. Thereafter, an upper limit and a lower limit (forexample, ±10%) are determined from the regression line of the powers andthe solar radiation values, and a numeric value that exceeds the upperlimit and the lower limit of the regression line is used as the powerloss due to the maximum power point tracking.

According to an embodiment of the present invention, a problem can besolved that, when a solar cell module actually operates, whether or notefficacy of the solar cell module has been achieved as in a case oftheoretical efficacy cannot be effectively judged.

According to an embodiment of the present invention, the referencemodule and the evaluation module are used; the power generation data ofthe solar cell module and data detected by the respective sensors (suchas the temperature sensors, the rain gauge, the fine particle detector,the thermo-hygrometer, the anemovane and the solarimeter) are collected;the power generation loss of the solar cell module, including the powerloss due to dust accumulation, the power loss due to the operatingtemperature of the solar cell module and the power loss due to themaximum power point tracking, is calculated; and, by making a comparisonwith the rated output, the power loss of the solar cell module duringactual operation is calculated to timely reflect the power generationefficiency and to further issue an alarm and an advice.

Further, as a feature of an embodiment of the present invention,according to the characteristic calculation method that allows the powerloss of the solar cell module during actual operation to be calculatedby using the power loss due to dust accumulation, the power loss due tothe operating temperature of the solar cell module and the power lossdue to the maximum power point tracking and by making a comparison withthe rated output, an analysis report information, including operationand maintenance reference information (such as whether or not cleaningis a need; whether or not a material has degraded; and, when the powergeneration efficiency is lower than expected, whether or not it isnecessary to perform maintenance or to replace the solar cell module),can be periodically provided to personnel of a power plant.

A solar cell module efficacy monitoring system and monitoring methodtherefor according to embodiments of the present invention can be usedin a field such as power generation using solar cell modules. Therefore,the present invention has industrial applicability.

Environmental factors have large effects on the power generationefficiency of a solar cell module. For example, factors such climate,season, and day and night affect the solar radiation amount. Further,dirt and dust on a solar cell module cause the power generation amountto decrease. However, it is difficult to determine a relationshipbetween dust accumulation and a decrease in power generation efficiency.Further, power output of a solar cell module is also affected by thetemperature of the module when the module is actually used. The higherthe temperature of the module is, the lower the power output is.Therefore, a system and a method are needed that allow factors causingdecrease in the power generation efficiency of a solar cell module to beclearly identified.

Further, current technologies of solar cell modules have been developedon the premise that the power generation efficiency of the solar cellmodules is improved. However, there is no technology for performingevaluation of the power generation efficiency of the solar cell modules.A technical feature of an embodiment of the present invention is thatrelevant data of a solar cell module during operation is collected usingexisting sensors and actual operation efficiency of the solar cellmodule is evaluated using a specific calculation method.

A solar cell module efficacy monitoring system according to anembodiment of the present invention and a monitoring method thereforaccording to an embodiment of the present invention allow the powergeneration loss of a solar cell module, including the power loss due todust accumulation, the power loss due to the operating temperature ofthe solar cell module and the power loss due to the maximum power pointtracking, to be calculated, and allow the power loss of the solar cellmodule during actual operation to be calculated, by making a comparisonwith the rated output, to timely reflect the power generation efficiencyand to further issue an alarm and an advice.

According to an embodiment of the present invention, a solar cell moduleefficacy monitoring system provides power generation status of a solarcell module to a user by calculating and monitoring power loss of thesolar cell module due to dust accumulation, and includes: a referencemodule that is a solar power generation module and a surface of which isconstantly maintained in a clean condition; an evaluation module that isa solar power generation module and a surface of which is covered bydust in an actual environment; two maximum power point tracking devicesthat, by being respectively connected to the reference module and theevaluation module, respectively track powers of the two modules andmaintain power outputs of the two modules at maximum points; a PVcommunication recording device that, by being connected to the referencemodule and the evaluation module, records power generation results ofthe two modules; and a calculation display device that, by beingconnected to the PV communication recording device, calculates powerloss of the evaluation module due to dust accumulation.

According to another embodiment of the present invention, a solar cellmodule efficacy monitoring system provides power generation status of asolar cell module to a user by calculating and monitoring power loss dueto operating temperature of the solar cell module, and includes: areference module that is a solar power generation module and a surfaceof which is constantly maintained in a clean condition; an evaluationmodule that is a solar power generation module and a surface of which iscovered by dust in an actual environment; two maximum power pointtracking devices that, by being respectively connected to the referencemodule and the evaluation module, respectively track powers of the twomodules and maintain power outputs of the two modules at maximum points;a sensor communication recording device that includes two temperaturesensors and records operating temperatures of the reference module andthe evaluation module that are detected by the two temperature sensors;a PV communication recording device that, by being connected to thereference module and the evaluation module, records power generationresults of the two modules; and a calculation display device that, bybeing connected to the sensor communication recording device and the PVcommunication recording device, calculates power loss due to theoperating temperature of the evaluation module.

According to yet another embodiment of the present invention, a solarcell module efficacy monitoring system provides power generation statusof a solar cell module to a user by calculating and monitoring powerloss of the solar cell module due to maximum power point tracking, andincludes: a reference module that is a solar power generation module anda surface of which is constantly maintained in a clean condition; anevaluation module that is a solar power generation module and a surfaceof which is covered by dust in an actual environment; two maximum powerpoint tracking devices that are respectively connected to the referencemodule and the evaluation module, respectively track powers of the twomodules and maintain power outputs of the two modules at maximum points;a sensor communication recording device that includes a solarimeter andrecords a solar radiation amount in the environment that is detected bythe solarimeter; a PV communication recording device that, by beingconnected to the reference module and the evaluation module, recordspower generation results of the two modules; and a calculation displaydevice that, by being connected to the sensor communication recordingdevice and the PV communication recording device, calculates power lossof the evaluation module due to the maximum power point tracking.

According to yet another embodiment of the present invention, a solarcell module efficacy monitoring system provides power generation statusof a solar cell module to a user by calculating and monitoring powerloss of the solar cell module during actual operation, and includes: areference module that is a solar power generation module and a surfaceof which is constantly maintained in a clean condition; an evaluationmodule that is a solar power generation module and a surface of which iscovered by dust in an actual environment; two maximum power pointtracking devices that are respectively connected to the reference moduleand the evaluation module, respectively track powers of the two modulesand maintain power outputs of the two modules at maximum points; a PVcommunication recording device that, by being connected to the referencemodule and the evaluation module, records power generation results ofthe two modules; a sensor communication recording device that includestwo temperature sensors that detect operating temperatures of thereference module and the evaluation module and a solarimeter and recordsresults that are detected by the sensors; a calculation display devicethat, by being connected to the sensor communication recording deviceand the PV communication recording device, calculates each of power lossdue to dust accumulation, power loss due to the operating temperatureand power loss due to the maximum power point tracking of the evaluationmodule, and, by making a comparison with a rated output of the referencemodule, calculates power loss of the evaluation module during actualoperation.

According to yet another embodiment of the present invention, power loss(Δp) of a solar cell module during actual operation is calculated fromthe following Formula 1: power loss (Δp) of the solar cell module duringactual operation=rated output of a solar cell module−(actual generatedpower of the solar cell module+ΔPd+ΔPt+ΔPm) . . . Formula 1, where therated output of a solar cell module is a rated output of a solar cellmodule (reference module) of which a surface is maintained in a cleancondition; the actual generated power of the solar cell module is powergenerated by a solar cell module (evaluation module) of which a surfaceis covered by dust; ΔPd is power loss due to dust accumulation; ΔPt ispower loss due to operating temperature; and ΔPm is power loss due tomaximum power point tracking.

In a solar cell module efficacy monitoring system according to anembodiment of the present invention and a monitoring method thereforaccording to an embodiment of the present invention, the powergeneration loss of a solar cell module, including the power loss due todust accumulation, the power loss due to the operating temperature ofthe solar cell module and the power loss due to the maximum power pointtracking can be calculated, and, by making a comparison with the ratedoutput, the power loss of the solar cell module during actual operationcan be calculated to timely reflect the power generation efficiency andto further issue an alarm and an advice. A solar cell module efficacymonitoring system according to an embodiment of the present inventionand a monitoring method therefor according to an embodiment of thepresent invention may be mounted on an inverter, or a part of aconfiguration thereof may be an inverter. Further, the dust in anembodiment of the present invention includes various factors that causepower loss and that occur on a surface of a solar cell module, such assand, pollen, fallen leaves and bird droppings.

Obviously, numerous modifications and variations of the presentinvention are possible in light of the above teachings. It is thereforeto be understood that within the scope of the appended claims, theinvention may be practiced otherwise than as specifically describedherein.

What is claimed is:
 1. A solar cell module efficacy monitoring system,comprising: a reference solar power generation module configured to bemaintained in a clean condition; an evaluation solar power generationmodule; a recording device, connected to the reference solar powergeneration module and the evaluation solar power generation module, thatrecords power generation results of the reference solar power generationmodule and the evaluation solar power generation module; and acalculation display device, connected to the recording device,configured to calculate power loss due to accumulation of dust on theevaluation solar power generation module.
 2. The solar cell moduleefficacy monitoring system according to claim 1, further comprising aplurality of temperature sensors and configured to record operatingtemperature of the reference solar power generation module and operatingtemperature of the evaluation solar power generation module detected bythe temperature sensors, wherein the sensor communication recordingdevice is configured to be connected to the calculation display device.3. The solar cell module efficacy monitoring system according to claim1, further comprising a solarimeter configured to measure an amount ofsolar radiation and configured to record the amount of solar radiationmeasured by the solarimeter, wherein the sensor communication recordingdevice is configured to be connected to the calculation display device.4. The solar cell module efficacy monitoring system according to claim1, wherein the reference solar power generation module, the evaluationsolar power generation module, the recording device and the calculationdisplay device are configured to transmit data between each other one ofwire transmission, wireless transmission and power line transmission. 5.The solar cell module efficacy monitoring system according to claim 1,further comprising a cleaning device connected to the reference solarpower generation module and configured to clean the reference solarpower generation module.
 6. The solar cell module efficacy monitoringsystem according to claim 5, wherein the cleaning device is configuredto recycle and reuse washing liquid.
 7. A method for solar cell moduleefficacy monitoring, the method comprising: providing a reference solarpower generation module configured to be maintained in a cleancondition; providing an evaluation solar power generation module;recording power generation results of the reference solar powergeneration module and the evaluation solar power generation module; andcomparing the power generation results of the reference solar powergeneration module and the evaluation solar power generation module todetermine power loss due to accumulation of dust on the evaluation solarpower generation module.
 8. The monitoring method of claim 7 furthercomprising recording a temperature of the reference solar powergeneration module and the evaluation solar power generation module. 9.The monitoring method of claim 7 further comprising measuring andrecording an amount of solar radiation of the reference solar powergeneration module and the evaluation solar power generation module. 10.The monitoring method of claim 7 further comprising cleaning thereference solar power generation module.
 11. A solar cell moduleefficacy monitoring system, comprising: a reference solar powergeneration module configured to be maintained in a clean condition; acleaning device adjacent the reference solar power generation module andconfigured to clean the reference solar power generation module; anevaluation solar power generation module; a PV communication recordingdevice, connected to the reference solar power generation module and theevaluation solar power generation module, that records power generationresults of the reference solar power generation module and theevaluation solar power generation module; and a calculation displaydevice, connected to the PV communication recording device, configuredto calculate power loss due to accumulation of dust on the evaluationmodule.
 12. The solar cell module efficacy monitoring system accordingto claim 11, wherein the cleaning device is configured to recycle andreuse washing liquid.